Stability improvement of a liquid enzyme product.

The shelf-life of a previously developed two-part liquid-liquid enzyme ceruminolytic product was improved maintaining the same final reconstituted composition and re-formulating the liquid enzyme portion as a drug granulate by a double wet granulation process. The critical steps for the preparation of the granulate were studied (mixing/granulating times and drying) determining the proteolytic activity, the residual ethanol, and the moisture content of the granulates. The original liquid-liquid formulation had been proven effective as a ceruminolytic agent, but only had stability of greater than 75% enzyme activity for up to 18 months and up to 1 day at room temperature after combining the two parts. The resulting improved product was proven to be stable for up to 24 months at 30 degrees C, and up to 3 days at room temperature after combining the two parts. Therefore, maintaining the enzyme in a granulated form until reconstitution afforded an improvement in stability compared with the original two-part liquid-liquid formulation.

Development of a liquid enzyme-based ceruminolytic product.

Various compositions for removal of human cerumen are marketed but they are not very effective. Therefore, a proteolytic enzyme-based ceruminolytic product was developed containing the enzyme, methyl trypsin, and sodium bicarbonate. Efficacy was optimized based on in vitro testing using both human and artificial cerumen preparations. Both qualitative (visual observation) and quantitative (spectrophotometric) assessments of ceruminolytic efficacy were employed. Optimal enzyme stability was observed for the aqueous formulation at pH 4, while greater ceruminolytic efficacy was observed at pH 8. The optimal concentration range of enzyme was 150-300 absorbance U/mL based on efficacy and stability considerations. An aqueous formulation containing both methyl trypsin and sodium bicarbonate was shown to be more effective than two commercial products, Murine Ear Wax Removal Drops and Cerumenex Ear Drops. A two-part packaging system was employed to provide adequate shelf-life. Long-term stability studies confirmed that the formulation maintained >75% enzyme stability for 24 months at 5 and 25 degrees C and after reconstitution at room temperature for up to 1 day.